A 52 year old woman presents with several months of bilateral lower extremity pain and knee swelling. More recently she reports arthralgias, as well as difficulty climbing stairs and standing from a sitting position. Included in her evaluation was a lower extremity MRI to evaluate for inflammatory myopathy/myositis:
Images demonstrate increased STIR signal along the periosteal surfaces of both femurs and proximal tibias. There is edema within the adjacent anterior compartment muscles of the lower thigh. Moderate bilateral knee effusions with intra-articular bodies are also noted.
Findings are indicative of bilateral diffuse periostitis, with synovitis of both knee joints and mild edema within the anterior compartment musculature of the lower thighs. The patient also underwent a Tc99m MDP bone scan:
Imaging findings in this case are characteristic of Hypertrophic Pulmonary Osteoarthropathy.
This condition, more generally known as hypertrophic osteoarthropathy, is believed to represent a reactive process in the bones due to elevated levels of circulating growth factors and cytokines. This was classically described in patients with pulmonary malignancy or infection, but other reported etiologies include chronic lung disease, pleural tumors/infection, endocarditis/vasculitis, gastrointestinal infection, inflammatory bowel disease, and hematologic malignancy. The patient in this case was diagnosed with pulmonary adenocarcinoma:
Joint effusions and pain are common in hypertrophic osteoarthropathy and may be the presenting symptom. Treatment of the underlying cause may result in improvement or resolution of this condition.
